The major objective of this project is to do a careful comparative study of the glycoproteins of the surface membrane of animal cells following virus transformation or during differentiation. Glycoproteins and glycopeptides removed from the surface enzymatically or solubilized with lithium 3,5-diiodosalicylate are being compared by gel filtration, disc gel electrophoresis and ion exchange chromatography. The systems under investigation include cells transformed by both RNA and DNA tumor viruses and mouse neuroblastoma cells before and during neurite extension. Gel filtration of glycopeptides from transformed and control cells has revealed quantitative and qualitative differences. These same glycopeptides can be resolved into 13 different fractions by ion exchange chromatography. The same method resolves tryptic peptides into 8 fractions. Intact glycoproteins are resolved into 2 to 4 different fractions depending upon the source of the material. Differences have also been noted between the glycoproteins from the inner membranes of the cell and those found on the cell surface. In addition, an apparently new sialyl transferase has been discovered whose activity increases 5 to 11 fold following virus transformation. Disc gel electrophoresis of lithium diiodosalicylate solubilized glycoproteins reveals 1 major glycoprotein and 3 minor ones. Future work will include detailed carbohydrate and peptide analysis as well as immunological studies of these glycoproteins and their location on cell surfaces.